I have a couple of small merc/mariner questions. Just aquired a nice 6hp 1995 Mariner. Have done preliminary checks. all looks good except maybe the compression. Both cylinders read 90-93 lbs. engine warm, both plugs removed, throttle wide open during test. Is this acceptable compression. Motor cranks first pull, idles smooth, runs out good in a test tank. Second question, I want to change this 6hp to a 8hp or a 9.9. Specifically what is the difference besides the carb? maybe exhaust tube? thanks for your time, ben
